Mere Christianity, Episode 22 ~ Book 3, Chapter 8: The Great Sin

In his famous teaching on the sin of Pride in this chapter, Lewis builds a strong argument on why this particular sin is the most insidious and deadly for Christians: "According to Christian teachers, the essential vice, the utmost evil, is Pride. Unchastity, anger, greed, drunkenness, and all that, are mere flea bites in comparison: it was through Pride that the devil became the devil: Pride leads to every other vice: it is the complete anti-God state of mind."